making a linear power supply safer.

[ELS122]

so I know the need for proper fusing and ground but that's about it, MOV's and all those other things are a mistery to me.
I want to make this transformer/power supply for a tube amp safer or more reliable or anything that's usefull, benefitial and isn't like rocket science to do.

also what is the use for C6?
I pretty much never seen this.
also I've seen caps across rectifier diodes so is that benefitial?
also I've read about putting a 625V 1650V? mov from the plates to the center tap of the output transformer.
I am using EL84's with a lower plate voltage of about 380V in my case (yes I know...)
and should I use like a 425v mov?

[Vovk_Z]

To it was reliable you definitely don't have to use КЦ401Б.

[Kleinstein]

The capacitor C6 has some sense in EMI suppression and it also takes some of the magnetizing current of the transformer (this does not make much of a difference with a large transformer). It also limits the rate of voltage change and this way is a little similar to the capacitors parallel to the diodes.

Tube circuits tend to use some extra filtering after the rectifier, so if a MOV is used  at all the question is a little where to place it. It could well be only after the filtering - but it depends how well those parts handle overload.

[Vovk_Z]

also what is the use for C6?

- put 100 R ... 470 R resistor in series with that capacitor, to it was fully functioning RC-snubber. Of cause, because of high voltages, here we can use serial connection of parts, for example, two serial connected 100 R 1 W resistors, two serial connected 0.01 uF 1000V capasitors (C6), etc.
We can use usual power diodes here, again, for example, serial connected 1N4007, etc.